COMPARATIVE STUDY OF DITYLENCHUS DESTRUCTOR THORNE, 1945 (NEMATODA:TYLENCHIDAE), FROM POTATO, BULBOUS IRIS, AND DAHLIA, WITH A DISCUSSION OF DE MAN'S RATIOS

Nematodes having the general characters of Ditylenchus destructor Thorne, 1945, from the potato, bulbous iris, and dahlia, did not reveal any significant difference in the basic structures to suggest the presence of more than one species. However, due to host influence, there may be some variation in total length, width, number and arrangement of sex cells, length of oesophagus, length of spear, and tail shape. Nematodes from potato were successfully transferred to dahlia and carrot, and from iris and dahlia to potato.Specimens of D. destructor from potato interbreed freely with specimens from bulbous iris and from dahlia. Evidently these nematodes from the three hosts are the same species, i.e., D. destructor.Among the ratios used, the values of c in the case of males and that of "V%" have some support from the data.